Surface Characteristics, Optical and Electrical Properties on Sol-Gel Synthesized Sn-Doped ZnO Thin Film

Abstract

Un-doped ZnO and Sn-doped ZnO (SZO) thin films were synthesized using the sol-gel method. The surface morphology of the SZO films showed a large amount of crystallization. Doping with tin dopants not only reduced the surface roughness of the film, but also repaired defects in the pore structure. Notably, the SZO film with a crystallization temperature of 650°C possessed better crystallization and fewer defects when tin dopants were added. XPS analysis confirmed the presence of O-Sn4+ phases proving the contribution of tin doping on the electrical conductivity of the SZO films. With regards the PL spectra, luminescence in the Zn2SnO4 phase was observed and affected the red-shifted of broad visible emission. In addition, the 9 at% Sn doped ZnO (S9ZO) film showed excellent optical transmittance, however the transmittance improved further when the trace of tin dopants (0.4 at%) and 2 at% In were doped in ZnO matrix (I2S0.4ZO).